1. Field of the Invention
The present invention relates to a transmitter for sending a message from a data processing unit such as a host computer in real-time over a plurality of bus lines on the basis of a window protocol.
2. Description of the Prior Art
A conventional zeal-time message transmitter using a window protocol is adapted to send a message from a data processing unit such as a host computer to a designated different message transmitter over a single bus line. To this end, the conventional message transmitter monitors whether the bus line is occupied by the different message transmitter and sends the message to the different message transmitter for a time period that the bus line is not occupied by the different message transmitter in accordance with the monitored result. For this reason, the conventional real-time message transmitter has a disadvantage in that it cannot send the message in a proper time because the bus line may be occupied for a long time by the different message transmitter. This disadvantage of the conventional real-time message transmitter becomes more prominent as the message to be sent is increased in amount.
To solve the above problem, there has recently been proposed a message transmission network having a plurality of bus lines. However, a conventional message transmitter employed in the multi-bus message transmission network cannot send the message in the proper time as before because it controls the bus lines individually.